Drill.



J. A. BARR.

DRILL.

APPLICATION FILED mm: a, 1908.

awn/Whoa John 14.54/71 Patented Apr. 13, 1909.

ami/moms m Mowers psrzns c0-. WASHINGTON. 0. c.

UNiTidi) JOHN A. BARR, OF ZOLLARSVILLE, PENNSYLVANIA.

DRILL.

Patented April 13, 1909:

Serial No. 37,372.

T 0 all whom. it may concern:

Be it known that I, JOHN A. BARR, a citizen of the United States, residing at Zollarsville, in the county of Washington and State of Pennsylvania, have invented certain new and useful Improvements in Drills; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to rock drills, and particularly to that class of device used for drilling blast holes in coal or other soft bodies.

The object of the invention is to provide a device of this character whereby the blast hole may be enlarged considerably after a certain predetermined depth of hole has been drilled.

A further object of the invention is to pro vide means located within the drill handle for operating the bits so that they are spread to drill such a hole.

With these and other objects in view, the invention consists of certain novel features of construction, combination and arrangement of parts, as will be more fully described and particularly pointed out in the appended claim.

In the drawings, Figure 1 is a front elevation, Fig. 2 is a side elevation, Fig. 3 is a longitudinal sectional view, Fig. 4 is a fragmentary detail front elevation with parts broken away and showing the knives in 6X- posed position, Fig. 5 is a transverse sectional view on the line 5-5 of Fig. 1.

Referring more especially to the drawings, 1 represents a tubular shank, which is provided at its outer end with a bit supporting member 2, having a pair of cutting knives 3, pivoted between the bifurcated end thereof by means of a pivotal pin 4. The outer ends of these knives are curved outwardly as shown in Fig. 2, and provided with cutting edges 6. The inner end or the one located between the jaws and the bit supporting member 2 is inclined from one side to another as at 7, so as to be properly engaged by the knife operating rod 8, which passes through the member 2, and the shank 1. In

orderto aline the operating rod 8 I preferably thread a T-coupling 9, 0n the inner end i of the shank 1 and insert in the end thereof a threaded nut 10, adapted to receive the threaded inner end 11, of the operating rod keyed thereto an operating handle 12, so that the rod may be easily operated through the shank to engage the cutting knives.

The T n el: 13, of the coupling 9 has socured within it the crank shaft operating handle 14, which has an extra bend 15, to accommodate the rod handle 12, so that it will not come into engagement with the operators hand. The opposite end of the crank is provided with the usual knob 16, swiveled thereto.

In operation, the knives are in the position shown in Fig. 1. The hole is drilled to the required distance by turning the crank arm 1-1, and then the handle 12 is operated to force the operating rod against the inclined inner ends of the knives so as to spread them and consequently their forward ends. This enlarges their cutting scope and consequently the hole being drilled. 'io withdraw the device the operating handle is reversed to its fullest ext ent. The drill may then be pulled. directly out, the sides of the knives engaging the walls of the aperture formed to force them to their normal position.

From the foregoing description, taken in connection with the accompanying drawings, the construction and operation of the invention will be readily understood without requiring a more extended explanation.

Various changes in the form, proportion and the minor details of construction may be resorted to without departing from the principle or sacrificing any of the advantages of this invention deiined in the appended. claim.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

In a rock drill, an operating shank, a pair of knives pivotally cured thereto, a U- shaped crank secured to the shank, a brace knob journaled on the end of said crank in alinement with the shank, a handle formed 8. The utmost extremity of this rod has on said crank offset with respect to the shank,- In testimony whereof I have hereunto set an operating rod extending through and my hand in presence of two subscribing Witthreaded into the shank and adapted to en nesses.

gage and operate the knives to expand the JOHN A. BARR. cutting points thereof, anda crank handle 5 Witnesses: for operating said rod which lies within the I JOHN G. GAYMAN, U-shaped crank. I JAMES BURNE. 

